Is the rate of biodiversity loss increasing or decreasing?
Compared to the 1.6 million species known about on Earth, the number of recorded extinctions can seem very low. Since 1500AD there have been 711 vertebrates, and around 600 invertebrates and plants known to have gone extinct but the actual number is likely to be considerably greater. In the future, it is predicted that extinction rates are likely to further increase more than ten-fold over coming decades.
Humans have been affecting global biodiversity for tens of thousands of years. There may have been extinctions which we do not know about. However, extinctions are now estimated to be occurring perhaps at least ten to a hundred times faster than they were in pre-human times. If that continues, the number of extinctions is likely to increase dramatically.
Currently 37,400 animal and plant species are known to be threatened with extinction – roughly 28% of the 134,000 assessed by the International Union for Conservation of Nature (IUCN) Red List. The true figure is expected to be far higher when accounting for the total number of species on the planet.
One recent assessment by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services found that as many as 1 million animal and plant species are now threatened with extinction – more than ever before in human history.
Much of the reason for the acceleration in extinctions is the growing pressure on species from human-driven land and coastal use change, over-exploitation, climate change, pollution and invasive alien species.
Although there has been an expansion of protected areas both on land and in the oceans since 2000, this will not compensate for species already lost. According to the World Wildlife Fund's Living Planet Report 2020, the animal populations they assessed decreased by an average of 68% between 1970 and 2016.
Climate change is expected to place further pressure on these diminishing populations by altering habitats and triggering extreme events such as more frequent wildfires and flooding. It may also promote the spread of invasive species and diseases with the result that many already threatened species are likely to be pushed over the edge to extinction in the decades to come.
To find out more Past and future decline and extinction of species | Royal Society